This invention relates in general to laser imaging systems and more particularly to a laser diode imaging system having improved laser beam alignment in the optics module.
Laser imaging systems are commonly used in scanning and printing applications. In one scanning application, an unmodulated laser beam from a laser scans an image on film or hard copy to produce a raster image which is detected and further utilized. In another scanning application, a storage phosphor storing a latent x-ray image is scanned to produce an emitted x-ray image which is detected and further utilized. In a printing application the laser beam is modulated with image information to expose photosensitive media such as film, paper, electrophotographic media or the like.
In laser imaging systems, it is very important for a laser imager that the laser beam is well-defined in shape, direction and collimation. There are various solutions to this problem which use mirrors and/or prisms to give the laser beam the correct direction. One of the problems with achieving alignment, if a semiconductor laser source is used, is that the Z-axis locations (parallel to the optical axis) of the collimating lens relative to the laser diode has to be held constant at all times while the pair is moved around in the X-Y plane (perpendicular to the optical axis). Some applications require an additional glass plate or lens to control the laser diode output via feedback to a detector device. This requires an even more accurate steering of the laser beam directly after collimation is achieved.
Current art has the laser diode mounted permanently to the laser driver board. This causes problems when an adjustment needs to be made to the alignment of the laser beam. The laser diode then needs to be unsoldered from the board, repositioned, and then remounted to the driver board. This series of steps is not only time consuming but poses significant static and heat risks to the laser diode and the driver board. A second problem is that the manufacturing tolerances of the lens, laser diode, and current mounting system are too loose. Because of this, lateral alignment is very difficult to achieve.
According to the present invention, there is provided a solution to these problems.
According to a feature of the present invention, there is provided a laser diode which projects a laser beam along a first optical axis;
a collimation lens positioned along said first optical axis for collimating said laser beam; and
an assembly for mounting said laser diode and said collimation lens for selective rotation about said first, optical axis and for rotation about second and third mutually perpendicular axes which are also perpendicular to said first, optical axis in order to effect rotation of said laser beam about said first, second and third axes.
The invention has the following advantages.
1. The biggest advantage is that the risk of heat and static damage caused by re-soldering a laser diode during an alignment process is reduced to a minimum.
2. In addition, the assembly and adjustment time is significantly reduced.
3. The collimating lens can be adjusted perpendicular to its optical axis.